Introduction to Cell Biology PDF

WELCOME NEW CLASS Prof Dr. Hala Elmazar 1 Prof Dr Hala Elmazar 2 Prof Dr Hala Elmazar 3  Best wishes Think positive It is going to be hard, but hard does not mean impossible Don’t stop when you’re tired stop when you’re done...

WELCOME NEW CLASS Prof Dr. Hala Elmazar 1 Prof Dr Hala Elmazar 2 Prof Dr Hala Elmazar 3  Best wishes Think positive It is going to be hard, but hard does not mean impossible Don’t stop when you’re tired stop when you’re done Best wishes Prof Dr. Hala Elmazar 4 Introduction To Cell Biology Prof Dr. Hala Elmazar 5  Cell Biology The study of normal cells structures & functions (Cellular & Molecular levels) The cell is the smallest & the basic unit of a living body ( The cell can carry on all the process of life) The living body is made of different types of cells Cells varies in size from 4 to 200 microns. The living organisms are either unicellular or multicellular The cell can't be seen by naked eye but only by microscope Prof Dr. Hala Elmazar 6 Histology ( histo: tissue, ology : science): Microscopic study of tissues of the body and how these tissues form the organs Cells Tissue Organ Prof Dr. Hala Elmazar 7  Body extracellular Cells matrix Prof Dr. Hala Elmazar 8  1- The cell The cells are classified into : 1.Prokaryote 2.Eukaryote Prokaryotic cell: lacks the nucleus, the genetic material (Genophore) is located in the cytoplasm in area called Nucleoid & has No membrane bounded cell organelles Eukaryotic cell contains nucleus & membrane bounded organelles. Both ( Pro & Eu ) share 4 key elements ( cell membrane, cytoplasm, genetic material, ribosomes) Prof Dr. Hala Elmazar 9  Prokaryote cell The DNA strand is circular and is called gonophore and found in area called nucleoid Prokaryotes by process called Binary fission Prof Dr. Hala Elmazar 10 Eukaryote cell Equivalent lengths: 1 millimeter (mm) = 1000 micrometer (micron) 1 micrometer (um)= 1000 nanometer 1 nanometer(nm)= 10 angstrom Prof Dr. Hala Elmazar 11 Prokaryote vs. Eukaryote Prof Dr. Hala Elmazar 12 There are around 200 cell types in the human body. Cell types look different and carry out different functions Different types of cells of the body Prof Dr. Hala Elmazar 13 The 4 basic types of tissues that make the human body 1- Epithelial tissue : refers to groups of cells that cover the exterior surfaces of the body, line internal cavities and passageways, and form certain glands 2- Connective tissue : binds the cells and organs of the body together 3- Muscular tissue: contracts forcefully when excited, providing movement 4- Nervous tissue: is also excitable, allowing for the generation and propagation of electrochemical signals in the form of nerve impulses that communicate between different regions of the body Prof Dr. Hala Elmazar 14 2- 1- 3- 4- Prof Dr. Hala Elmazar 15  2- Extracellular matrix (ECM) is the substance (non cellular) that fills the spaces between cells & it is secreted by the cells Composed of proteins and other molecules that surround, support, and give structure to cells and tissues in the body. The extracellular matrix helps cells attach to, and communicate with, nearby cells, and plays an important role in cell growth, cell movement, and other cell functions Prof Dr. Hala Elmazar 16  Types of Extracellular matrix (ECM) The ECM has two basic forms 1-Basement Membrane 2-Interstitial fluid is sheet-like depositions of ECM thin layer of fluid surrounds the at the base of epithelial cells cells : H₂O, proteins, electrolytes, surround muscle cells acids, hormones , waste materials (only found under epithelial cells) Prof Dr. Hala Elmazar 17  Most epithelial cells are separated from the connective tissue beneath it by a sheet of extracellular material called basement membrane The basement membrane is usually visible with light microscope Is formed by 2 layers basal lamina & reticular lamina Basement membrane 18  The basal lamina itself is visible with EM about 20 -100 nm in thickness. secreted by epithelial cells Basal lamina consists of 2 layers lamina lucida & lamina densa NB: in diabetes mellitus , the basement membrane of small blood vessels especially in retina & kidney became thick Prof Dr. Hala Elmazar 19  The main components of basal lamina are: type IV (4) collagen The reticular lamina is formed by reticular fibers, usually thicker than basal lamina, secreted by connective tissue cells (fibroblasts) Prof Dr. Hala Elmazar 20  Epithelia tissue compose of cells laid together in sheet & tightly connected to one another. Epithelial cells are avascular but innervated so it gets its nourishment from the underlying connective tissue Function of basement membrane : 1- Anchoring epithelial cells to underlying tissue, 2- pathway for cell migration, 3- wound healing, 4- barrier between epithelial cells & CT, 5- participate in filtration of blood in kidney, 6- early stages in cancer called carcinoma in situ ( limited to epithelial layer) Prof Dr. Hala Elmazar 21  Plasma Membrane: also called cell membrane surrounds the cell & separates the interior of the cell from the outside & provides protection for the cell Basal Lamina: thin sheet of ECM which are made by and located underneath the epithelial cells Basement Membrane: sheet-like form of extra cellular matrix underlie epithelial cells & surround muscle cells Intracellular Matrix: the substance that fill the inside of the cell = cytoplasm Prof Dr. Hala Elmazar 22  ECM amount varies according to tissue type (minimal in epithelium and plenty in connective tissue ECM consistency varies: It may be jelly like e.g. connective tissue proper It may be rubbery e.g. cartilage It may be hard e.g. bone It may be fluid e.g. blood Functions: 1-Support of cells 2-Supply of nutrition and oxygen, communication 3-Removal of waste products Prof Dr. Hala Elmazar 23 ECM in blood ECM in bone ECM in cartilage ECM in CT proper Prof Dr. Hala Elmazar 24  Organization of the human body Human body is organized as follow: 1. Cells 2. Tissues 3. Organs 4. Systems Prof Dr. Hala Elmazar 25  Tissues Each basic tissue is formed of special types of cells have the same general features and perform specific functions. The four basic tissues are: 1. Epithelial tissue 2. Connective tissue 3. Muscular tissue 4. Nervous tissue Prof Dr. Hala Elmazar 26  Organs Each organ is formed of different kinds of tissues that perform together a special function. Examples of organs : The kidney The liver The lung The stomach Prof Dr. Hala Elmazar 27  Systems A system is an organization of different organs that together perform integrated complex functions of the body. Examples of systems : The urinary system The digestive system The respiratory system Prof Dr. Hala Elmazar 28  Methods Of Studying Cell Biology Cell culture: isolating the cells and make them grow under controlled conditions Cell fractionation: Separate cellular components while persevering the individual functions of each component by breaking the cells by process called centrifugation Chromatography: chemical analysis done in the lab for separation of a mixture into its component composed of 2 phases mobile & stationary phase Prof Dr. Hala Elmazar 29  Electrophoresis: separating of charged molecules using an electrical field ( size & charge) Genetic technology: study the structure and function of genes ( Isolating gene, copy genes = cloning, determine unknown DNA sequence Gel electrophoresis recombinant DNA technology Prof Dr. Hala Elmazar 30  Microscopy Is the standard optical instrument for generating magnified image & to examination of histological Types: 1.Light microscope (LM) 2.Electron microscope (Transmission and scanning) 3.Phase contrast microscope 4.Differential interphase microscope 5.Fluorescence microscope 6.Confocal microscope Prof Dr. Hala Elmazar 31  1- Light microscopy (LM) The widely used microscope LM uses visible light source + condenser lens (to send light through the object). The image of this object is magnified by two sets of lenses: 1. Ocular lens (10) 2. Objective lenses (5 ,10 , 40) Total magnification power = 1 x 2 e.g.10 X40 =400X times Prof Dr. Hala Elmazar 32  The capacity of microscopes depends on: 1.Magnification power: the power to enlarge objects. 2. The resolution power : is the smallest distance between two particles that can still be seen by eye or camera as two separate objects & not a as single object ( done by : lenses) The magnification valuable only when accompanied by high resolution. The resolution power of: 1. Healthy naked eye = 0.2 millimeter 2. L M = 0.2 micrometer (um) 3. EM = 0.2 nanometer (nm) Prof Dr. Hala Elmazar 33  Equivalent lengths: 1 millimeter (mm) = 1000 micrometer (micron) 1 micrometer (um)= 1000 nanometer 1 nanometer(nm)= 10 angstrom Binocular light microscopy Prof Dr. Hala Elmazar 34  6- The Electron Microscope (EM) Technique is used to obtain high resolution images Beam of electrons is used as source of light The image is formed from the interaction of the electrons with the specimen as the beam travelling through it Beam passes through a vacuum tube The lenses are electromagnetic coils instead of glass lenses Prof Dr. Hala Elmazar 35  The lenses are electromagnetic coils instead of glass lenses Electromagnetic lens Illuminating system consists of: Consists of: electron gun & condenser lens Condenser lens is capable of generating circular magnetic felid that act to focus electrons on the specimen Prof Dr. Hala Elmazar 36 Imaging system consists of : A- Another electromagnetic lenses (2-3) B- Screen The objective lens is used to refocusing the electrons after they pass through the specimen & form image The projector lens is to enlarge the image of the object and projecting it into the fluorescent screen Prof Dr. Hala Elmazar 37  The image appears on screen plate which glows when being hit by electrons Images can be detected as: Light areas (electron lucent) & dark areas (electron dense) Corresponding to areas through which electrons readily passed Embedding in resin The tissues and cells need special preparation & then cut into Copper grid slides very thin sections (ultra thin sections = 0.01 of the micron) Then collected on a copper metal grid Prof Dr. Hala Elmazar 38  During preparation sections are stained with salts of heavy metals like lead nitrate and uranyl acetate that precipitate in tissues. EM can magnify the image thousands of times(up to 200.000 times). The resolution power = 0.2 nanometer(nm) For permanent records, photos are made Prof Dr. Hala Elmazar 39  Types of EM Transmission EM (TEM) :where electron beams pass through the specimen. It shows the details of internal structures of cells. Resolution power: 0.2 nanometer TEM SEM Scanning EM (SEM) :a special type of EM where electron beams are reflected from the surface of coated specimen. This gives a three dimensional image of a specimen. Resolution power: 10 nanometer Prof Dr. Hala Elmazar 40  3-Phase contrast microscope It depends on the idea that some lens systems can produce visible images from transparent objects (unstained). The principal is that light changes speed when passes through cellular and extracellular structures & with different refractive indices. Objects appear lighter or darker to each others. It is useful in examining living cells & tissue cultures e.g. blood cells and sperms Prof Dr. Hala Elmazar 41  4- Differential interphase contrast microscope is advanced version of phase contrast microscope ( used for transparent or unstained samples). The obtained image appears three dimensional characters. It utilizes two separate beams of light. DIC microscopy Prof Dr. Hala Elmazar 42  5- Fluorescence Microscopy Certain substances absorb invisible ultraviolet light of short wavelength and emit (reflect) it as visible light of long wavelength and are known to exhibit fluorescence (physical property). This microscope is provided with special lamp that can emit ultraviolet rays which pass through the tissue. It can be used to visualize DNA, RNA, proteins and antigen antibody complex (antibodies labeled with fluorescence) Prof Dr. Hala Elmazar 43  6- Confocal Laser Microscope (3D) * The illumination is provided by a laser source. The specimen should be labeled by fluorescent molecules Uses: increase optical resolution and contrast (better image) The LASER light passes through a small hole (to avoid photo bleaching) to examine fine details It is connected to a computer system to reconstruct full image of the specimen Prof Dr. Hala Elmazar 44 LM & EM Prof Dr. Hala Elmazar 45 Prof Dr. Hala Elmazar 46